Pentax 67 light leak?

Discussion in 'Medium Format Cameras and Accessories' started by Marco Buonocore, Oct 12, 2013.

  1. Marco Buonocore

    Marco Buonocore Member

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    Hello,

    I've been testing a Pentax 67 kit. I'm very much enjoying the lens selection that came with it, mostly wide angles, which I don't usually get to play with.

    Problem is, there is a consistent defect in the negatives I'm processing. About 9mm from the right hand side of the neg there is a thin white line. It prints as black. It's on every neg, on multiple rolls. You can see it on the following photo:

    fence-off-mechanic-ave-for-APUG.jpg

    Any guesses as to what it is, and how the problem can be addressed?

    Thank you!
     
  2. Toby Key

    Toby Key Member

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    That line looks to me like you have dust in the calibration area of a flat bed scanner. Are you observing this on the negs with a loupe, or just on scans? It can't be a light leak they look nothing like that, and it would be white on the print.
     
  3. jovo

    jovo Membership Council

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    Looks like something in your developing tank is scratching the negative. When that happens, the scratch is clear, and it prints black. It's such a straight and thin line that I can't think of anything else it might be, particularly as it is consistent with other developed rolls of film. It won't show up in the rebate, of course since the rebate between negs is clear, but if it traverses the whole roll, it's a scratch for sure. What tank do you use?
     
  4. Marco Buonocore

    Marco Buonocore Member

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    Toby: it's not dust on the scanner; I'm scanning 8"x10" prints. I can see it on the neg under a loupe, and on the baseboard while enlarging.

    John: I don't think it's something scratching during the development. The reason I say this is the mark is running up and down the "6" part of a 6x7 neg - it's not running down the length of the roll. Does that make sense? I process a lot of 120 film, normally shot on my Rolleiflex TLR. I use Patterson tanks and reels. The mark is on every one of the four rolls I've shot on the camera - the negs were processed at different times.
     
  5. momus

    momus Subscriber

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    Doesn't look like a light leak. I'd suspect shutter bounce, but that's just a guess. Does it happen on every speed, or just the highest speeds?.
     
  6. Marco Buonocore

    Marco Buonocore Member

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    Hi Momus,

    Most of the time that I've been using this camera, I've been using it at night with 'B' setting - with the mirror locked up. When I'm in the darkroom next I'll look at some negs that were not shot at night and see if the issue is still there.

    Thanks,
     
  7. erikg

    erikg Member

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    Can't be a light leak if it prints black, but I can't think what might cause this. Perhaps something physically in the way, thread or hair? Guessing here.
     
  8. Marco Buonocore

    Marco Buonocore Member

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    Hello erikg,

    You're right - it can't be a light leak. Sometimes it's hard to wrap ones head around the problem!

    Your idea about it being a thread or hair was a good one. I put the camera up on a tripod, put the mirror up and put the shutter on bulb. I used a flashlight and looked very carefully but could find nothing.

    It's a shame, as the camera itself is in wonderful shape and the lenses are immaculate. It might remain a mystery!
     
  9. Hatchetman

    Hatchetman Subscriber

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    On every frame of every roll?
     
  10. Marco Buonocore

    Marco Buonocore Member

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    Yes, it's on every frame on every roll. It is very faint, mind you, and is essentially hidden if there is detail in the image where the line is. If there is sky, like the image in the initial post, it is very evident.
     
  11. erikg

    erikg Member

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    Same spot on each frame? That points to a camera issue. Have you done a test roll recently?
     
  12. momus

    momus Subscriber

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    I re looked, and it isn't shutter bounce. That looks totally different. As has been stated, if it's black on the print, then it can't be light leaks. What an odd problem. It probably isn't shutter related. There has to be something thin obstructing the film, right? I can't imagine that it's a developing issue. What's left?
     
  13. rsank

    rsank Member

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    I have had something looking like this with my Chinese Seagull clone TLR, the 645 mask was so badly machined that it was causing scratches on the negative and it would result in several black lines on prints and scans. Could be something inside the camera scratching the emulsion on the film?
     
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  15. Marco Buonocore

    Marco Buonocore Member

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    Hello rsank,

    It's hard to imagine how it could be a scratch - the film travels left to right in the pentax 67, and these marks run up and down the film.

    I agree with momus that it looks like some sort of obstruction, but I've looked carefully at all the lenses, inside the body and on the lens hood. I see nothing.

    Very frustrating! I was quite excited to make this my new night photography camera!
     
  16. sbjornda

    sbjornda Member

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    I've never seen scratches going perpendicular to motion of film travel before, that show up on every frame. Do you have access to another camera that would take 120-sized film from your batch? Maybe there's something wrong with the batch of film, or something in the processing. It would be good to know whether you can eliminate the camera and lenses as the variable.
     
  17. Marco Buonocore

    Marco Buonocore Member

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    Hello sbjornda,

    I have two other 120 camera; a Rolleiflex TLR that I use frequently, and a Mamiya 645 that I use less so. I don't see this problem on those cameras. I don't think it's a problem with the film, as the mark in question appears in the same place on the 6x7 neg(9mm from the right hand side of the neg) on every frame. To me, that indicative of something in camera, not a film defect.
     
  18. erikg

    erikg Member

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    Yes, a film issue seems unlikely. I still think it is (or was) an obstruction. Maybe it's gone now, have you tested the camera since you looked it over?
     
  19. Salem

    Salem Member

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    Since the shutter travels horizontally and the line is horizontal it could be shutter problem. I would think that this could be tested by shooting in daytime at speed slower than 1/30 (sync speed) and see if you still get the line.
     
  20. jwatts

    jwatts Member

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    I get this line on some of my images as well. I process at a lab, and I thought it was a lab mistake. It does not happen in every frame, maybe because I usually am shooting below 125.

    My shutter is starting to go out (now only works from 250 and below) so it would make sense to me that it is another shutter related issue.
     
  21. Marco Buonocore

    Marco Buonocore Member

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    Hello jwatts,

    Any chance you could post a scan of an image?

    Like I mentioned, I have mainly been using this camera on the bulb setting, and holding the shutter open for 2 to 8 minutes. The image in the original post was a 2 min exposure.

    Next time I have some free time I'm going to take a series of shots with different lenses and different shutter speeds of a clear north sky and see if it will make it easier to determine what's going wrong.
     
  22. jwatts

    jwatts Member

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    Marco,

    Actually I just went to find a good example scan for you and realize that this was probably a 15sec exposure. sometimes its very evident like in the example im posting, sometimes its more faint. It also comes and goes, 2-3 clear rolls, then one roll will have it in 2-3 frames. I'd really love to track down the culprit of it. I hope is something a CLA will take care of.

    88520009.jpg Screen Shot 2013-10-22 at 12.22.22 PM.png
     
  23. John Wiegerink

    John Wiegerink Member

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    That doesn't look like any light leak I've ever seen??? It almost looks like something (glue, etc.) stuck to a roller, pressure plate(220 film). Can you tell if it's on the emulsion side or backing side by holding it on an angle to the light. What ever it is it's something new to me. JohnW
     
  24. sbjornda

    sbjornda Member

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    If I didn't know better I'd say it was a problem with a scanner. It looks digital, pixelated, up close. Barring that, the closest thing I've seen is when, during development, the film is mis-wound onto the reel & parts of it stick together. But that shouldn't happen at the same place on every frame.
     
  25. John Wiegerink

    John Wiegerink Member

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    If it can't be a film problem or processor problem then it has to be a camera problem. Since you are not getting it with the Rollei I'd guess you might want to check your first shutter curtain and your second (follower) shutter curtain. Shine a bright light(those little multi-bulb LED flashlights work great for this) in the front of the camera with the lens off, mirror lifted up if possible, and look from the backside at the curtain. Do this in a near dark room. Could be an insect riddled shutter curtain. Don't laugh! I've seen curtain cloth damaged by little odd grubs that like chewing on that type of material for some odd reason. JohnW
     
  26. erikg

    erikg Member

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    A hole in a shutter would cause fog, or pinspots of light, not dark lines. Either something is blocking light from the film or something is scratching the emulsion side, although I can't think of what that might be in a Pentax 6x7. JWatts image looks like an emulsion scratch or abrasion. The marks are similar to clip marks you might see on sheet film done at a lab using a dip and dunk processor. Again I can't think of what might cause this particular case. Now I really want to know!